Table 3. Experimental Program.

groups	particle size (mm)	immersion time (h)	number
A	0.1–0.2	raw	A-1
		Washed	A-2
		24	A-3
		48	A-4
		72	A-5
B	0.2–0.5	raw	B-1
		washed	B-2
		24	B-3
		48	B-4
		72	B-5
C	0.5–1.0	raw	C-1
		washed	C-2
		24	C-3
		48	C-4
		72	C-5